The invention relates to an occlusion device for the closure of a physical anomaly such as a vascular aperture or an aperture in a septum, such as patent ductus arteriosus, atrial septal defect, patent foramen ovale, or ventricular septal defect comprising an occluding body extending at least within the aperture with a center piece extending in the axial direction of said occluding body as well as wire-like, elastic fixation devices emanating from the occluding body or its center piece, the ends of said fixation devices being thickened to have a spherical or lenticular shape or provided with spherical or lenticular elements.
The human circulatory system is comprised of a cardiovascular circulation and pulmonary circulation. In the embryonic phase of the development of a human being, the two circulatory systems are joined by the ductus arteriosus. The ductus connects the aorta (systemic circulation) with the pulmonary artery (pulmonary circulation). In the normal development of an infant, this ductus closes after birth. In pathological development, the ductus may not close so that the two circulatory systems remain connected even after birth. This can reduce the life expectancy of the infant.
Closure of the ductus by means of a surgical procedure is well-known. However, this procedure is very cost-intensive and is connected with a risk for the patient.
Closure of the ductus by means of an IVALON.RTM. (polyvinyl alcohol) foam plug (Porstmann method) is also well-known. In this case, a guide rail is introduced via a femoral vein into the aorta, through the ductus into the pulmonary artery and from there through the right ventricle and the right atrium and finally to the outside again via the opposite femoral vein. The ductus plug is then pushed into the ductus where it is "jammed in place." Owing to the high pressure differential1 between the aorta and pulmonary artery, high demands are placed on the fixation of the ductus plug within the ductus.
For that reason, relatively large plugs must be used which are compressed by about 10 times their length and are 30% larger than the diameter of the ductus. Correspondingly large sheaths are required for introduction of the plug into the femoral artery. In infants, the diameter of the vessels is small and is often not large enough for a procedure of this nature in children weighing less than 30 kg.
In an occlusion device disclosed in DD 233 303 A1, the occluding body has a single-shell, hyperboloid-like basic shape and can be comprised of metal, a metal alloy, plastic and similar materials. Wire-like fixation devices extend outside the occluding body and end in a point so that the risk of injuring vascular walls exists.
In order to implant the occlusion device, it is grasped by a holding wire extending within a safety sleeve and advanced by a catheter. Due to the shape of the occluding body and the pointed ends of the fixation devices, the possibility of withdrawing an improperly implanted occlusion device is associated with considerable danger of injury to the patient.
WO 94/09 706 discloses an occlusion device having a helical basic body from which filaments emanate which evoke clot formation
A prosthesis for the closure of an atrial or ventricular septal defect is described in DE 42 22 291 C1. The prosthesis is comprised of a center piece wich is pretensioned via an extension spring from which center piece arms emanate which are in contact with the vascular wall. U.S. Pat. No. 3,874,388 discloses an occlusion device having a basic body from the ends of which fixation devices exercising the effect of an umbrella emanate which can be brought into contact with vascular walls.
In the case of the generic occlusion device according to EP 0 698 373 A2, an injury to the vascular walls by the fixation devices is ruled out. This results in the advantage that a change of position of the occluder itself is readily possible during implantation of the occlusion device. The spherical or lenticular ends of the fixation devices also ensure that if there is a high pressure differential between the vessels joined by the ductus, the fixation elements which are normally in contact with the internal walls of the vessel cannot lead to an injury resulting from movement of the occlusion device. The spherical ends also prevent injury even if the device is possibly transported through the vessels without the protection of a catheter.